The invention relates to the folding fin system described in the following, in particular a self-locking folding fin concept that was realized with the goals of robustness, reliability, and minimizing manufacturing costs. This folding fin was attained by using the fewest possible components, production parts with a design that is optimized for function and production, and by employing standard components.
Folding fin systems are known from the prior art, for example, in EP 1 628 112 A1. Folding fin systems are always used when a guided missile requires a fin for stabilizing its flight, but at the same time must be launched from a generally cylindrical launch tube. In this case folding fin systems are used, wherein the fin is folded in so that the missile can be placed in the launch tube. As soon as the missile is launched and leaves the launch tube, the fin moves to its unfolded condition so that the missile may be guided.
In known systems, however, it is disadvantageous that the systems are extremely complex and thus expensive to produce. In addition, known systems may not be used for a number of missiles; in particular known system are not scalable or adaptable.
It is therefore an object of the invention to provide a folding fin system that may be used for a plurality of missiles, while being simpler and more cost-effective to manufacture and assemble, and that in particular may be easily scaled or adapted.
This object is attained using a folding fin system that includes a fin root and an upper fin part. The upper fin part is rotatably borne on the fin root. The upper fin part may be moved between an unfolded position and a folded position using a movement of the upper fin part relative to the fin root. The movement is in particular a rotation of the upper fin part relative to the fin root. It is inventively provided that the fin root and the upper fin part may be locked relative to one another using a key-and-slot system when the upper fin part is in the unfolded position. Locking by means of key and slot ensures that the upper fin part cannot be moved out of the unfolded position. Thus, it is assured that the folding fin system can develop its fin effect without this being interrupted by the upper fin part folding inadvertently. The fin root may be applied and attached, in particular, from outside to a missile casing, especially using attaching elements such as screws, rivets, or an adhesive bond. In addition to being characterized by robustness and reliability, as has already been verified numerous times during an ejection test, the folding fin is also characterized by the possibility of scaling and simple adaptation to other missiles, since the fins do not engage in the casing of the missile. The fin root may be produced integrally with the missile section (e.g., precision extrusion molding) or may be applied to the missile section from the outside.
It is preferably provided that the upper fin part is borne via an axis on the fin root. To this end, the fin root has a first axial mount, while the fin upper part has a second axial mount. The axis is arranged inside of the first axial mount and the second axial mount. Moreover, it is preferably provided that the first axial mount includes at least one first axial mount element and the second axis includes at least one second axial mount element. Particularly advantageously, a plurality of first axial mount elements and a plurality of second axial mount elements are present, wherein, in particular, the number of first axial mount elements is equal to the number of second axial mount elements. Advantageously, the axis is guided alternately inside the first axial mount element and the second axial mount element. This provides a connection of the upper fin part to the fin root in the manner of a hinge.
Particularly preferred, exactly one second axial mount element is allocated to each first axial mount element. The first axial mount element has a slot, while the allocated second axial mount element has a corresponding key. In an alternative embodiment, the first axial mount element has a key, while the allocated second axial mount element has a corresponding slot. Thus the aforesaid key-and-slot system is realized especially in the first axial mount and second axial mount, particularly advantageously in the first axial mount element and second axial mount element. The term “allocated” here shall especially be construed to mean that the slot or key of the first axial mount element may be caused to engage with the key or slot of the allocated second axial mount element such that the aforesaid locking is realized. In particular, it is provided that keys and slots exclusively of allocated first axial mount elements and second axial mount elements may be caused to engage with one another.
In addition, it is particularly advantageous when the key may be inserted into the slot parallel to the axis using a relative movement between upper fin part and fin root. Thus, a rotation about the axis is required for unfolding the folding fin system, i.e., for moving the upper fin part into the unfolded position, while a translation along the axis is required for locking the upper fin part to the fin root. This separation of movements ensures secure and reliable locking.
Each key and/or slot has a tapered area with conically tapering flanks and an end area with parallel flanks. It is particularly advantageous when the conically tapering flanks are chamfers in the parallel flanks. Thus, in particular, it is provided that for inserting the key into the slot, first the tapered area of the key must be inserted into the tapered area of the slot, which is facilitated by the conically tapering flanks or chamfers. As soon as the key is completely inserted into the slot, the flanks of the end areas block a relative movement between key and slot in all directions except along the insertion direction of the key into the slot. Thus, in particular, a rotation of the upper fin part about the axis is prevented.
Furthermore, it is preferably provided that borne on the axis is an elastic element that presses each first axial mount element against the allocated second axial mount element. Particularly advantageously, the elastic element is a compression spring. Particularly advantageously, the compression spring is supported against a first end of the axis and against a first axial mount element. At the same time, it is provided that a second end of the axis is supported against a second axial mount element. In this manner, the axis is continuously tensioned so that the first axial mount element and the allocated second axial mount element are always pressed against one another. Thus it is assured that the relative movement between upper fin part and fin root that is required for inserting the key into the slot is automatically performed when the upper fin part is in the unfolded position. For releasing the lock, this means for removing the key from the slot, a movement of the upper fin part relative to the fin root would have to be performed against the elastic spring effect of the elastic element, especially the compression spring. The translation required for locking preferably occurs opposing the flight direction of the folding fin system, so that inertia during acceleration and aerodynamic forces amplify the effect of the elastic element and cannot weaken.
The first axial mount element or the second axial mount element preferably has a stop that blocks a movement of the upper fin part relative to the fin root beyond the unfolded position. Thus, it is ensured that, when there is an unfolding movement of the upper fin part relative to the fin root, the upper fin part is stopped in the unfolded position so that the key can be inserted into the slot, which means the blocking or locking of the upper fin part relative to the fin root occurs.
In addition, the folding fin system preferably has an elastic rotary element, wherein a spring force of the elastic rotary element urges the upper fin part into the unfolded position. Thus an external force must act on the folding fin system, especially on the upper fin part, to retain the upper fin part in the folded position. As soon as this external force is removed, the spring force of the elastic rotary element causes the upper fin part to execute a movement relative to the fin root to be moved into the unfolded position. In particular if the aforesaid stop is present, the upper fin part is pressed against the stop by the elastic rotary element. If, in addition, the described elastic element is borne on the axis, the folding fin system is automatically locked, since the key is inserted into the slot by the elastic spring force of the elastic element.
The elastic rotary element is particularly preferably a leg spring. In addition, it is provided that the elastic rotary element has a first leg that is inserted into a bore of the upper fin part. It is also preferably provided that the elastic rotary element has a second leg that is positioned at an angle to the first leg about a pre-tensioning/biasing angle. The magnitude of the pre-tensioning/biasing angle permits, in particular, a pretension of the elastic rotary element to be set. The second leg is advantageously positioned against the fin root or is disposed in a pocket in the fin root provided for this purpose. If the elastic rotary element, especially the leg spring, is embodied symmetrically, it is also alternatively provided that the first leg is positioned against the upper fin part instead of being guided in a bore of the upper fin part.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.